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xray physics > week 11 xray > Flashcards

week 11 xray Flashcards

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1
Q

bergonie and tribondeau

A

metabolism, maturation and differention will govern which cells are more or less radiosensitive

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2
Q

physical factor of linear transfer function

A

the rate at which energy is transfered through the matter it is going through and it loses energy

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3
Q

units of linear energy transfer

A

keV/micrometer

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4
Q

how much energy is being loss per unit distance is defined as

A

linear energy transfer function

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5
Q

REB stands for

A

Relative biological effectiveness

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6
Q

REB is expressed in terms of?

A

comparison between a “standard” radiation type and some other type of ionizing radiation

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7
Q

fractionation is defined as?

A

breaking the total dose into smaller individual doses separated in time.

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8
Q

radio sensitivity physical factors?

A

fractionation
LET
Protraction

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9
Q

Protraction is defined as?

A

the total dose is continuously administered over an extended the time period

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10
Q

Both fractionation and protraction can reduce the biological effects of ionizing radiation- why?

A

Because cells can repair radiation damage

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11
Q

early effects of radiation

A

Effect manifests within minutes to days of exposure

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12
Q

Late =

A

Effect manifests in months to years

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13
Q

biologic effect:

A

oxygen effect and age
Radiosensitizing and radioprotective agents have been identified
Radiosensitizing agents

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14
Q

Oxygen effect

A

Increased oxygenation increases radiosensitivity of tissues

Oxygen effect is LET dependent- there is more oxygenation effect for low LET radiation.

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15
Q

Age biological effects

A

Sensitivity is greatest in utero birth and decreases until age 30; levels off and increases again in advanced age

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16
Q

dose response relationships

A

how much radiation vs how much response was observed

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17
Q

how can a dose response relationship be described as

A

linear vs non-linear

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18
Q

threshold vs nonthreshold relationship is used to describe what about the dose response relationship

A

place where something starts at a particular set of dose and the nonthreshold is a a response when any amount of dose is given

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19
Q

ambient level of response

A

means level of response present without or prior to any intervention

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20
Q

will a curve that goes in to the ambient level be easy to see or hard to see?

A

hard

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21
Q

the government uses radiation safety guidelines and estimating the biological effects of radiation

A

a linear, non-threshold dose-response model is used.

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22
Q

most important macromolecule for radiation exposure?

A

DNA

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23
Q

3 main radiation effects on macromolecules

A

breaking of main chain
crosslinking
point linking

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24
Q

Cross-linking

defined as?

A

Formation of new chemical bonds that link side-chains with one another

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25
Q

crosslinking results in

A

Results in increased viscosity of a macromolecular solution

26
Q

point lesion is defined as?

A

Disruption or alteration of single chemical bonds

Changes in the cell may be undetectable to the repair mechanisms of the intracellular environment.

27
Q

DNA and irradiation- 3 effects

A

Cell death

Malignant disease

Genetic damage

28
Q

Most likely molecule to interact with a photon is ____?

A

water

29
Q

Free radicals are

A

uncharged, highly reactive molecules or atoms with a single electron in their outer valence orbital.

30
Q

____________ also result from combination of free radicals- this is an important component of radiation cell damage

A

Toxic substances

31
Q

is it the indirect or the direct mechanism that has an effect on humans?

A

indirect

32
Q

ALARA?

A

as little as reasonably possible

33
Q

All ______ effects, and most normal tissue _____effects are deterministic.

A

early, late

34
Q

Deterministic effects are characterized by

A

A threshold dose below which no effect is seen

Worsening of the effect as dose increases over the threshold

35
Q

Stochastic effects account for the remaining _____ effects

A

late

36
Q

does stochastic effects have a threshold for dose?

A

no

37
Q

is the severity of the effects of radiation dose related?

A

no

38
Q

Stochastic effects include

A

radiation carcinogenesis and hereditary effects.

39
Q

Stochastic Effects expressed as?

A

statistically/ likelyhoods

40
Q

early effects of radiation

A

Acute Radiation Syndrome
Local tissue damage
Cytogenetic damage

41
Q

Acute Radiation Syndrome

A

Hematologic effects
Gastrointestinal effects
Central Nervous system effects

42
Q

Local tissue damage

A

Skin
Gonads
Extremities

43
Q

Cytogenetic damage

A

Observable with DNA analysis

44
Q

Late Effects

A

Leukemia

Other malignant disease

Local tissue damage
Decreased life span

Genetic Damage

45
Q

In utero radiation effects

A

Prenatal death

Neonatal death

Congenital malformation

Childhood malignancy

Decreased growth and developmento

46
Q

early effects general consept of body area and radiation intensity?

A

For a given level of radiation intensity, the larger the body area exposed, the greater the effect

47
Q

prodromal syndrome and a latent period is seen in

A

acute radiation syndrome.. which signifies that more symptoms are coming

48
Q

Prodromal period/ Prodromal syndrome

occurs at doses

A

> 100 rads whole body

49
Q

s/s of Prodromal period/ Prodromal syndrome

A

diarrhea, nausea, vomiting, Leucopenia

Followed quickly by manifest ARS if dose is high

50
Q

Latent period may follow the prodrome

A

A period of relative recovery from prodromal symptoms

May last from hours to weeks

51
Q

blood count changes as what rem?

A

50

52
Q

vomitng occurs at twhat rem?

A

100

53
Q

mortality dose

A

150 rem

54
Q

LD

A

320-360

55
Q

100% mortality

A

800 rem

56
Q

the LD 50/60 is defined as

A

the dose at thiwch 50% the exposed pop. will die within 60 days

57
Q

for human beings the LD 50/60 is estimated at_____ rads whole body exposure

A

350

58
Q

early effects on local tissue

A

Erythema
Epilation
Desquamation

59
Q

what can happen to the reproductive organs of male around 10 rads

A

sterility

60
Q

at what level is sterility is temporary?

A

200

61
Q

at what level is sterility is permenant?

A

500 rads

xray physics (1 decks)

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